Technical Field
This invention relates to an optical surgical probe and, more particularly, to a multi-spot laser surgical probe with a faceted distal surface.
Related Art
Optical surgical probes deliver light to a surgical region for a variety of applications. In some applications, it may be useful to deliver light to multiple spots in the surgical region. For example, in pan-retinal photocoagulation of retinal tissue, an optical surgical probe that is configured to split a single laser or light beam into multiple beams focused to multiple retinal spots can cause photocoagulation at these spots simultaneously. Photocoagulating at n=2, 4, 6 spots simultaneously can reduce the time of the pan-retinal photocoagulation procedure approximately by a factor of 2, 4, or 6.
Various probe designs have been employed to produce multiple beams for a multi-spot pattern. For example, some probes include a diffractive element to divide a single beam into multiple beams corresponding to higher diffractive orders. Such diffractive elements are typically positioned inside the surgical probe, as positioning them at the end of the probe would pose substantial design challenges. However, positioning the diffractive elements away from the end of the probe can limit their functionalities.
Therefore, another class of optical surgical probes split the incoming beams into beam components with a multi-spot generator that includes a faceted surface to split the incoming beam, and possibly a ball lens to focus the split beam components.
For either of these probes, a general challenge for the design of beam splitting probes is to fit them into a sufficiently small cannula at the end of the probe. The leading probes today have 23 Gauge cannulas, i.e. an outer diameter of about 0.650 mm. It is a non-obvious challenge to design the beam splitting elements to fit into these very narrow cannulas.
Finally, since in surgical practice the probes may be operated in a number of ways that differ from the recommended operating procedures, the probes need to be able to operate under a variety of conditions, not only under ideal ones. Such non-ideal conditions may include the probes being operated outside the eye, or being operated while having unplanned residue, including loose tissue, debris or blood blocking parts of the optical paths. Thus, a need persists for optical surgical probes that can produce well-controlled multiple spots at a surgical target region using optical elements that can fit into a narrow cannula at the probe's end, and they can do so under a variety of non-recommended conditions.